1. Field of the Invention
The present invention relates to a universal plug and play (UPnP) network system, and more particularly, to UPnP quality of service (QoS) for setting a path from a source device to a target device and explicitly controlling reservation of network resources in a home network that supports UPnP QoS and a method of reserving a path and resources thereof.
This work was supported by the IT R&D program of MIC/IITA[2004-S-605, Development of HD Level Interactive Multimedia Service Technology over Wireless Home Network].
2. Description of the Related Art
A UPnP technique allows communication without a complicate setting procedure among information home appliances connected to a network. In the UPnP techniques, it is possible for a device to automatically search for a service supported by another device.
In order to support QoS, a network system using the UPnP technique includes a UPnP QoS management device and one or more UPnP QoS execution devices. At this time, the UPnP QoS management device and each of the UPnP QoS execution devices is embodied as an internal system of a switch device or bridge device, or an independent device.
When a predetermined communication terminal requests the UPnP QoS management device to provide a service through a control point, the UPnP QoS management device obtains network status information on neighboring nodes connected to devices through the UPnP QoS execution devices.
The UPnP QoS management device calculates an optimal path from a predetermined communication terminal to a target communication terminal by using the obtained network status information. Then, the UPnP QoS management device requests all the UPnP QoS execution devices to provide the service and the QoS for the service by transmitting traffic feature information to all the UPnP QoS execution devices located on the calculated path.
Then, the UPnP QoS execution devices located on the calculated path selects and reserves network resources by referring to a media access control (MAC) address table managed by a bridge.
However, as described above, in a conventional network system, since the UPnP QoS execution device reserves the network resources according to the MAC address table managed by each bridge, a case where a path calculated by the UPnP QoS management device is different from a path through which the UPnP QoS execution device reserves resources may occur.
That is, a conventional UPnP QoS management device provides information for reserving resources to the UPnP QoS execution devices located on the calculated path. However, the conventional UPnP QoS management device does not provide information on which network resource is reserved for a device connected to two or more networks.
For example, as shown in FIG. 1, it is assumed that the UPnP network system includes a third communication terminal 33 connected to second and third UPnP QoS execution devices 22 and 23 and that the first UPnP QoS execution device 21 includes a MAC address table in which an address of the second UPnP QoS execution device 22 is stored as bridging information for the third communication terminal 33.
Then, the number of paths between the first and third communication terminals 31 and 33 is two. That is, there are a path including the first and second UPnP QoS execution devices 21 and 22 and a path including the first and third UPnP QoS execution devices 21 and 23.
A QoS management device 10 obtains a path including first and second UPnP QoS execution devices 21 and 22 as a path between the first and third communication terminals 31 and 33. Although the QoS management device 10 requests the first and third UPnP QoS execution devices 21 and 23 to provide the QoS, the first UPnP QoS execution device 21 unconditionally reserves network resources connected to the second UPnP QoS execution device 22.
Data of the first communication terminal 31 is transmitted to the second UPnP QoS execution device 23 through the first UPnP QoS execution device 21. However, since the second UPnP QoS execution device 22 does not reserve a network, it is impossible to satisfy the QoS for the requested service.
It is impossible to stably provide the QoS by using a method of reserving the network resources through the UPnP QoS execution device according to local information, that is, the MAC address table managed by the bridge, since the path through which the network resources are reserved is different from the calculated path.
Accordingly, in order to stably provide and secure the QoS for each service, it is necessary for the UPnP QoS execution device to reserve network resources along the path calculated by the QoS management device.